deserialize method

@override String? deserialize(DartType targetType, String expression, TypeHelperContextWithConfig context, bool defaultProvided,)

Returns Dart code that deserializes an expression representing a JSON literal to into targetType.

If targetType is not supported, returns null.

Let's say you want to deserialize a class Foo by taking an int stored in a JSON literal and calling the Foo.fromInt constructor.

Treating expression as a opaque Dart expression representing a JSON literal, the deserialize implementation could be a simple as:

String deserialize(DartType targetType, String expression) =>
  "new Foo.fromInt($expression)";
```.

Note that [targetType] is not used here. If you wanted to support many
types of [targetType] you could write:

```dart
String deserialize(DartType targetType, String expression) =>
  "new ${targetType.name}.fromInt($expression)";
```.

Implementation

@override
String? deserialize(
  DartType targetType,
  String expression,
  TypeHelperContextWithConfig context,
  bool defaultProvided,
) {
  if (!typeChecker.isExactlyType(targetType)) {
    return null;
  }
  final resolvedGenericType = genericType(targetType);

  var itemSubVal =
      context.deserialize(resolvedGenericType, closureArg)!.toString();

  final targetTypeIsNullable = defaultProvided || targetType.isNullableType;

  var output = '$expression as List';

  // If `itemSubVal` is the same and it's not a Set, then we don't need to do
  // anything fancy
  if (closureArg == itemSubVal && typeChecker.isExactlyType(targetType)) {
    return wrapNullableIfNecessary(
        expression,
        deserializeFromIterableExpression(output, resolvedGenericType),
        targetTypeIsNullable);
  }

  output = '($output)';

  if (closureArg != itemSubVal) {
    final lambda = LambdaResult.process(itemSubVal);
    output += '.map($lambda)';
  }

  output = deserializeFromIterableExpression(output, resolvedGenericType);

  return wrapNullableIfNecessary(expression, output, targetTypeIsNullable);
}